1. Field of the Invention
The present invention relates generally to the field of radiation-shielding materials. More specifically, the present invention discloses a radiation-shielding material using hydrogen-filled glass microspheres that can optionally be supplemented with metallic microspheres or powder, or solid glass microspheres.
2. Background
The effectiveness of a radiation-shielding material is characterized by its ability to absorb the energy of highly-energetic particles within the shield material and to minimize generation of secondary particles that may deteriorate the radiological and electronic system performance situation. It is well known that hydrogen is a very effective element for absorbing high-energy particles with minimum secondary particle effects. Therefore an effective radiation-shielding material can be made by incorporating high concentrations of hydrogen. But, these materials often lack other properties required for structural integrity and gamma ray attenuation. Various multifunctional candidate materials have been suggested and studied in the past by NASA, such as the possibility of using liquid hydrogen and methane as radiation protection and fuel materials simultaneously.
In addition, glass microspheres filled with hydrogen are one of the promising technologies proposed for hydrogen storage as an energy source for various applications. Lithium hydride has been proposed for use as a shielding material for nuclear propulsion spacecraft. Various forms of polymeric materials have been suggested such as polyethylene, and polysulfone and polyetherimide. These materials also show good structural integrity. Graphite nanofibers heavily impregnated with hydrogen may become viable in the future, and represent multifunctional space structural materials. Finally, aluminum has long been used as a spacecraft material and vast of experience has been accumulated in using this material as a structural material for spacecraft and radiation-protection boxes for electronic equipment.
The present invention combines elements from the prior art, as discussed above, by employing glass microspheres filled with high-pressure hydrogen gas as a radiation-shielding material. The microspheres can be embedded within a suitable structural skeleton (e.g., aluminum) with a suitable binder. This shielding material can be readily customized to various radiation field environments by adding different metals to the microspheres, such as lead, tantalum, or tungsten. In addition, metal powder, metal microspheres or solid glass microspheres can be included. The microspheres can also be filled with a combination of gases, or supplemented by other microspheres filled with different gases, such as helium-3, which has very high absorption cross-section for neutrons. The fraction of these microspheres within a structure can be selected for specific radiation field and radiation protection requirements.